WPD are raw data of actual work performed whereas WPR are report meant to to distribute to project stakeholders with specific purpose, there can be many variations of WPR based on who is the recipient, like variance report, status report, forecast report, quality report, Human resource report etc

If customer wants to accept deliverable by validating it w.r.t to required functionality they cannot do the same by looking at reports,

e.g : customer needs to validate web page response time can they do it with WPR?

The project performance reports will be reaching to customer from Manage Communication , so do not mix processes, just limit the Validate Scope to Validation of scope only, customer is not checking schedule variance , EV , and risks while doing validate scope, you have have different stakeholder to see deliverable and validate than project performance reports.

In validate scope, WPD is used to communicate to the customer about the amount of work done, number of change request raised for product/deliverable for nonconformity, number of testing done etc. In general, remember WPD comes from execution phase and is fed into validate scope process that is in M&C controlling phase. Refer to project information flow diagram on page 59 in PMBOK